1. Field of the Invention
The present invention relates to a semiconductor device including a semiconductor chip mounted on a wiring substrate.
2. Description of the Related Art
The integration degree of semiconductor chips has been increasing year by year. With the integration degree of the semiconductor chips increasing, the density, performance, and operation speed of the semiconductor chips have been improving. There has also been a demand for a reduction in the size and thickness of semiconductor devices (sometimes referred to as “semiconductor packages”) including semiconductor chips. A BGA (Ball Grid Array) structure or a CSP (Chip Size Package) structure, for example, are known as structures for which there is market demand that their sizes be reduced. In these structures, electrode pads on a semiconductor chip mounted on a wiring substrate are connected to wire bond pads on the wiring substrate by a bonding wire or the like. Furthermore, the semiconductor chip mounted on the wiring substrate is sealed with resin. Moreover, solder balls serving as external terminals are provided on a surface (hereinafter referred to as a “back surface”) of the wiring substrate located opposite a surface (hereinafter referred to as a “mounting surface”) on which the semiconductor chip is mounted.
Here, FIGS. 11 and 12 show a general structure of a semiconductor device (for example, a DRAM (Dynamic Random Access Memory) including a semiconductor chip with electrode pads arranged centrally thereon. FIG. 11 is a sectional view of semiconductor device 8. FIG. 12 is a plan view of a mounting surface side observed after formation of bonding wires (before sealing).
Illustrated semiconductor chip 1 is mounted according to face-up method (a circuit surface of the semiconductor chip faces the opposite side of the mounting surface of the wiring substrate) on the mounting surface of wiring substrate 2. Furthermore, bonding wires 3 are provided as shown in FIGS. 11 and 12 to connect respective electrode pads 4 provided on semiconductor chip 1 to corresponding wire bond pads 5 provided on wiring substrate 2.
In the above-described semiconductor device, the bonding wires, connecting the respective electrode pads provided on the circuit surface of the semiconductor chip to the corresponding wire bond pads provided on the mounting surface of the wiring substrate, need to avoid interfering with edge portions (ends) of the semiconductor chips. Thus, bonding wires 3 need to be shaped as shown in FIG. 11. As a result, wire bond pads 5 need to be provided away from each end of semiconductor chip 1. This increases distance (D1) between the end of semiconductor chip 1 and each wire bond pad 5 on wiring substrate 2. Moreover, distance (D2) between the end of semiconductor chip 1 and a corresponding end of semiconductor device 8 is increased. As a result, the size of semiconductor device 8 is increased.